University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) researchers have long extolled the virtues of individual protective covers (IPCs). Multi-county citrus Extension agent Edwin Gutierrez-Rodriguez does the same but also warns of potential risks. Following is information from a recent UF/IFAS blog article he authored.
In the ongoing battle against huanglongbing (HLB), also known as citrus greening disease, IPCs may be a powerful tool for Florida citrus growers. These mesh covers, designed to exclude (keep outside) the Asian citrus psyllid (ACP), vector of HLB, offer a non-chemical and cost-effective strategy to protect citrus trees at early stages, from planting during their most vulnerable years.
According to UF/IFAS research, as outlined in EDIS publication HS1425, IPCs exclude psyllids and prevent HLB infection. While the plants covered may remain HLB-free for up to three years, once uncovered, symptoms and positive results for the disease can take as little as six months to occur.
POTENTIAL PROBLEMS
Proper IPC installation and maintenance are fundamental. Covers should be secured right after planting, below the graft union, to PVC poles to prevent their collapse.IPCs can incur a liability if not properly maintained. The most common issues are:
- Weeds and grass growing inside the cover compete for water and nutrients, creating a humid microclimate that fosters pests and diseases.
- Overly tight fabric that constrains the stem can potentially cause mechanical damage and diseases.
- Accumulation of dust, soil particles and water can lead to the development of secondary pests and diseases.
- Branch deformation, due to limited space, is especially evident on vigorous growth cultivars.
- Light blockage can be caused by dust crusts or fungal growth, such as fumagine — a black, sooty mold that thrives on honeydew excreted by sap-sucking insects and reduces photosynthesis by blocking sunlight.
IPCs and citrus under protective screen (CUPS) may both modify the light and environment for citrus trees due to the cover material. While changes in light (wavelength and refraction) inside the covers can enhance photosynthesis and growth, excessive shading or deformation of branches can reduce light interception and hinder plant development.
RECOMMENDED ACTIONS
While plants are growing inside IPCs, make sure to:
- Inspect IPCs inside — at least seasonally and after storms.
- Replace IPCs when damaged or too small to allow trees to grow.
- Scout for pests and diseases, even inside.
- Make sure there is proper light and air circulation and avoid moisture buildup.
- Remove IPCs in a timely manner to prevent growth deformations.
Remember, before considering fancy strategies, technologies or fertilizers, citrus trees require their basic nutritional pillars — water, carbon dioxide and light. These are the true drivers of photosynthesis and growth. Without them, no nutrient program will succeed.
Source: UF/IFAS
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